Tharwa's Val Jeffery says he will more than likely contest a countback process when Zed Seselja resigns as a Member for Brindabella.
Mr Jeffery is one of two candidates who were unsuccessful at the October territory election who are most likely to claim the seat left by the former Opposition Leader when he vacates the Legislative Assembly.
The second is Homelessness Australia chief executive Nicole Lawder, who also stood for the Canberra Liberals in Brindabella.
Mr Jeffery has previously said he was keeping his options open in relation to any vacancy created by Mr Seselja.
But the 78-year-old general store owner said on Monday he was now ''reasonably confident'' he wanted take on the role of an MLA.
''The whole thing depends on the timing and the countback,'' Mr Jeffery said. ''But at this point in time, I'd be more likely to say yes rather than no.
''I'm reasonably positive that if I get in on the countback I'll take it on.
''After all, it's an opportunity I've been trying to get for years. Maybe I can get in and do something for my community.''
Elections ACT will begin its count-back process after Mr Seselja formally resigns from the Legislative Assembly.
The Opposition Leader has given no indication of his departure date, except that it will be before the official federal election campaign begins in August.
ACT electoral commissioner Phil Green said all Brindabella candidates who were unsuccessful in October would be notified after Mr Seselja's resignation and would have 10 days to indicate whether or not they would contest the casual vacancy.
The new MLA would be determined by distributing preferences from the votes Mr Seselja received at the election.
''We know from past experiences that most voters who vote for a major party candidate will show preferences for all other candidates in that party before showing preference for everyone else,'' Mr Green said.
''Assuming at least one of the two unsuccessful Liberal candidates stands for the vacancy, history suggests it will be one of those two candidates who fills the vacancy.''
Mr Green said Elections ACT had captured all preferences from all ballot papers at ACT elections since 2001 and could fill a vacancy by entering candidate names into its computer system.